
The cusp terms without imaginary parts arise from soft gluon exchanges between the initial-state heavy resonance and one of the final-state particles. The single-particle anomalous dimensions of the gauge fields vanish at one-loop order [1]}, [2]}, while the one-loop anomalous dimension of the heavy color-octet vector field is given by [3]}
\(\gamma ^{G^{\prime }} = - \frac{3\alpha _3}{2\pi } + \dots \,.\) 
